Pop singer spends the day with a 6-year-old Boston girl battling a rare form of brain cancer.

The young cancer patient received the surprise of a lifetime after pop sensation Justin Bieber flew her and her family to New York City to spend an entire "Valentine's Day" date in the Big Apple. According to MSNBC, the two played board games, signed autographs for each other, and Avalanna even was "able to lay her hands on the famous Bieber hairdo and style it her own way."

The fairy tale date was the result of an ambitious social media campaign started by Routh's family to get the young girl and Bieber in the same room. Naturally, she's a huge fan and after a particularly nasty round of chemo last year, her family threw her a "Bieber Wedding" with a cardboard cut-out of the star and a T-shirt that read: "The Future Mrs. Bieber."

When asked Monday (the same day the hashtag #MrsBieber trended worldwide on Twitter), how long she had been in love with the pop star, Routh responded “Seven years. No, 80. Eighty years.’’

The cancer Analanna is fighting is an atypical teratoid rhabdoid tumor (AT/RT) that is extremely rare and is diagnosed in less than 30 cases per year. According to Wikipedia, those with the disease over the age of 3 have an overall survival rate of 89 percent.

Bieber's effort to spend time with Routh follows in the footsteps of a similar action taken last December by his girlfriend Selena Gomez. The fellow pop star visited 13-year-old progeria patient Hana Hwang, after it was revealed that she was a huge fan. A heartwarming "thank you" video from the young teen to Gomez has since become an Internet sensation, with more than 2.2 million views.